For each exposure estimate, references are given in the last
column of the MOE table.

Exposure estimates assume 100% absorption.

Chemical Consumption in a Single Food

For consumption of a chemical in a single food, both the average
concentration of a chemical in that food and the average US
consumption of the food are used. The consumption of the chemical
in µg/day is as follows:

Consumption of the food (gm/day) × Chemical
concentration (ppm)

The amount in µg/day is converted to mg/day, and intake in
mg/kg/day is calculated as follows:

Chemical consumption from
the food (mg/day)
70 kg body weight person

Chemical Consumption in the Total Average
Diet

For chemical intake from consumption of all foods in the average
US diet, the value is reported in the reference. The calculation of
exposure in mg/kg/day is as follows:

Chemical consumption in
total diet (mg/day)
70 kg body weight person

Occupational Exposures to Workers

Average exposures to workers are for inhaled air in a specific
occupational category during specific years. Chemical
concentrations are reported in the table reference in milligrams
per cubic meter of workplace air. To calculate the concentration to
a daily dose rate in milligrams per kilogram body weight, an
assumption is used that a worker inhales 9.6 m3 of air
per 8-hour workday, weighs 70 kg, works 5 days per week 50 weeks
per year for 40 years, and has a standard lifespan of 70 years. The
calculation of exposure in mg/kg/day is as follows:

Air concentration (in
mg/m3) × 9.6 m3/day
70 kg body weight person

×

5 days/week
7 days

×

50 weeks/year
52 weeks

×

40 years work life
70 year life

Inhalation of Indoor Home Air

Average inhalation rates for indoor air are based on the US EPA
Exposure Factors Handbook (1997), which reports average breathing
rates for various types of activity and the number of hours spent
indoors. The values in the MOE table use an estimate of an average
adult spending 12 hours per day at home indoors and inhaling 7.72
m3/day. The calculation of exposure in mg/kg/day is as
follows:

Air concentration (in
mg/m3) × 7.72 m3/day
70 kg body weight person

Inhalation of Outdoor Air

Average inhalation rates for outdoor air are derived from the US
EPA Exposure Factors Handbook (1997), which reports average
breathing rates for various types of activity and the number of
hours spent outdoors. The values in the MOE table use an estimate
of an average adult spending 2 hours per day outdoors and inhaling
2.39 m3/day indoors. The calculation of exposure in
mg/kg/day is as follows:

Air concentration (in
mg/m3) × 2.39 m3/day
70 kg body weight person

Drinking Water

For consumption of a chemical in a single food, both the average
concentration of a chemical in that food and the average US
consumption of the food are used. The consumption of the chemical
in mg/day is as follows: